Speech audiometric materials incurrent use provide sensitivity to the existance of disorders of auditory function, but they lack specificity in defining processes leading to impaired speech perception. In the research proposed here we will manipulate the spectral, temporal and intensity parameters of synthetic and natural speech signals with the goal of better understanding the specific processes leading to impaired speech perception characteristic of sensorineural hearing disorders. In addition we will assess whether known abnormalities in the processing of simple acoustic signals can be related to abnormalities in the processing of the more complex acoustic parameters of speech. The specific aims of our research are: 1. To determine whether phonetic contrasts based solely on changes either in frequency, time or intensity cues are affected to the same extent by sensorineural hearing impairment. 2. To determine how the processing of spectral, temporal and intensity cues are affected by the configuration of the hearing impairment, by the etiology of the impairment and by the age of the listener. 3. To determine the correlation between abnormalities in frequency selectivity (as assessed by critical bands, masking functions and psychoacoustic tuning curves) and the identification of the several phonetic contrasts to be used in our experiments.